JPS58178981A - Method of sealing sheathed heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of sealing a sheathed heater in which a part of the opening is sealed with glass during the manufacture of the sheathed heater.

The conventional method for sealing the glass when manufacturing a sheathed heater is, for example, as shown in FIG.
At the same time, a glass sealing material 5, such as powder of low melting point glass, is put into the end opening of the sheath 1, and then the sheathed heater is placed in a heating furnace 11 having a heater 10 disposed therein. It was common practice to insert a 1 m section of the tube as shown in the figure, melt the glass sealing material 5, and remove it from the heating furnace 11 to complete the sealing.

In such a conventional sealing method, when heating the end of the pipe 1 to melt the glass sealing material 5, the heat at the end of the pipe 1 is transmitted to the entire mother pipe, raising the internal temperature of the pipe 1. , this result? The gas in f1 expands, and a part of it passes through the bath-molten glass sealing material 5 and escapes into the atmosphere. It is inevitable that the pressure will be significantly lower than atmospheric pressure. During this sealing process, when a part of the above-mentioned gas passes through the molten glass sealing material 5,
There was an extremely serious defect in which an opening for gas passage was created and the opening remained after sealing, resulting in poor sealing.

The present invention was made to solve these drawbacks,
The object of the present invention is to provide a method for sealing a sheathed heater with good electrical insulation properties without lowering the pressure of the gas sealed inside the pipe below atmospheric pressure when manufacturing the sheathed heater.

A specific embodiment of the present invention shown in FIG. 2 will be described below. In the second case, a heating coil 2 and a take-out terminal 3 connected to each other are inserted into the pipe 1, and magnesia powder 4 is filled therein, and a glass sealing material 5, such as a low-melting point glass powder, etc., is filled into the end opening of the mother tube 1. The glass sealing material 5 is inserted in the same manner as in the conventional example. Next, the end of the heating device 17F3, which has two heating units 6.6' such as heaters or high-frequency heating coils, is inserted.

One of the heating parts 6.6' of this heating device 7 is located on the main body side, slightly away from the end sealing part of the pipe 1, with respect to the other heating part 6'. is located at the end sealing part. When heating, first, the heating section 6 is operated to heat the portion of the pipe 1 facing the heating section 6.

By heating this part, 1 yen of gas is heated and expands, and escapes into the atmosphere from the end of pi f1. Next, the heating section 6 stops heating, and the heating section 6' is operated to similarly heat the opposite end of the pipe L, thereby sealing the glass sealing material 5 inserted there! Melt and seal. At this time, since the internal expansion gas has been released from the main body side in advance, new gas expansion does not occur, and therefore, the phenomenon of forming holes in the molten glass sealing material 5 does not occur at all.

As explained above, in the present invention, prior to heating the glass sealing material at the end of the pipe, the main body side is locally heated from the opening end of the pipe, and a gas of 197,941 yen is released into the atmosphere in advance. After that, the heating of this part is stopped and the sealing part is heated to melt the glass sealing material in that part in a bath.Therefore, the heating is performed in two stages, so that expanding gas is generated when the glass sealing material is melted. This solves the drawbacks caused by the occurrence of openings in the sealing part, and the internal pressure after sealing does not become lower than the atmospheric pressure as in the conventional case. As a result, the pressure in the iNiNi layer can be made higher than atmospheric pressure, resulting in a sheathed heater with extremely good electrical insulation properties. The heating sections 6, 6' do not necessarily need to be divided into two; for example, one heating section may be provided and the heating section may be moved or a sheathed heater may be moved. Further, it is preferable to make the heating temperature on the main body side higher than the heating temperature on the end portion because this can enhance the effect of releasing soot.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a conventional sheathed heater sealing method, and Fig. 2 is a cross-sectional view showing a sealing method according to the present invention. 1...Mother Iso, 2...Heating coil, 3...Grot terminal, 4...Magnesia, 5...Glass sealing material,
6... Heating section, 7... Heating device. Note that the middle portion of each drawing is designated by the corresponding reference numeral. Agent Shin Kuzuno - Figure 1 Figure 2

Claims (1)

[Claims] ・When sealing the ends of a sheathed heater that has a heating coil inside the flat iso and an extraction terminal and a glass sealing material on the ends, first heat the mother tube body side locally from the sealing point in advance. A method for sealing a sheathed heater, characterized in that the sheathed heater is sealed by heating a part of the sealing part to melt a glass sealing material introduced into the end.